I am in the enviable position of having a back yard full of established, heavily bearing citrus trees (minneola tangelo, satsuma, hamlin, kumquat, and navel). They are widely-spaced enough to allow light between them and there are some established azaleas and camellias planted in there, too. I have started to add some nectary plants and herb layers but no roots or vines so far, other than what nature has provided. I'm in the perfect area for using sweet potato as a ground cover. I'd love to plant sweet potato and jicama among the trees and let them cover the ground and climb the trees, but what about harvesting them? Citrus trees have shallow roots, you're not even supposed to mulch around them. Right now I am mowing to control the grass. I have asked the local master gardeners and the pro arborist who pruned the trees, none of them have ever tried this.

Will digging sweet potatoes and jicama harm my orange trees?
How far from the trunks should I plant the root layer?
If I plant the root layer out from under the canopy, is this far enough?

These trees are healthy and bear well. I do not want to do anything to endanger these trees! Anyone have experience growing multi-layer guilds with citrus trees?

There is a multi-layer practice out in the California desert with citrus trees -- they are used as the ground cover (lowest layer) in orchards of date palms. In those polycultures, the trees are allowed to keep their spherical shape down to ground level, and there is no light left for any sort of root layer. Citrus trees are pretty jealous about what is under their canopy and do best with no competition there (that's why it's important to keep the grass from growing under them. And if you stay outside of the canopy, well then you don't really have a companion planting, they are just next to one another.

Since you can't grow dates in Florida, you might want to try a jelly palm (Butia capitata) in between them. They do well in the humid South.

I have the same problem to solve...
I did not know that it as better to even control leaf-plants!
John, do you know what happens if they have some sort of competition?

I have planted a little out if the canopy, and unfortunately, the roots are going muuuuuuch further!!
And shallow for sure...

So yes I have damaged some roots, and nothing bad happened.
But, I know this is the best way to risk a fungal disease!

I lost an orange tree that was near the veggies: it was watered too regularly.
So strange that they have shallow roots and that they need quite a lot of water BUT do not like to be watered often!

does someone have an explanation about their behavior and tastes?

In S. Florida, I grew Malabar Spinach and Asian Winged Bean up mature citrus with no problems. As for sweet potatoes, I might hill them up out beyond the drip line and let them sprawl from there and see what happens.

Wish trading citrus scion were not a no-no. I would love to have Satsuma & Kumquat.

Malabar Spinach & Friend climbing Grapefruit: